Oral Care Composition

ABSTRACT

The present invention relates to an oral care composition with a high water content which has improved robustness towards microbial challenge. The oral care composition includes compositions comprising from 0.125 wt % to 0.75 wt % of a water soluble source of stannous ions, wherein the composition comprises at least 50 wt % water and wherein the source of stannous ions is selected from the group consisting of stannous chloride, stannous pyrophosphate, stannous formate, stannous acetate, stannous gluconate, stannous lactate, stannous tartrate, stannous oxalate, stannous malonate, stannous citrate, stannous ethylene glyoxide, and mixtures thereof.

BACKGROUND OF THE INVENTION

Compositions having a high water content tend to support the survivaland growth of microorganisms. This problem also occurs in oral carecompositions which have a high water content. Therefore, preservativeagents such as benzyl alcohol, methylparaben, propylparaben are oftenadded to oral care compositions in order to increase their robustnesstowards microbial challenge.

However, a need still exists for oral care compositions which haveimproved robustness towards microbial attack without requiring thepresence of preservative agents in the compositions.

SUMMARY OF THE INVENTION

A first aspect of the present invention provides an aqueous oral carecomposition comprising from 0.125 wt % to 0.75 wt % of a water solublesource of stannous ions, wherein the composition comprises at least 50wt % water and wherein the source of stannous ions is selected from thegroup consisting of stannous chloride, stannous pyrophosphate, stannousformate, stannous acetate, stannous gluconate, stannous lactate,stannous tartrate, stannous oxalate, stannous malonate, stannouscitrate, stannous ethylene glyoxide, and mixtures thereof.

Optionally, the composition comprises from 0.125 wt % to 0.75 wt % ofthe source of stannous ions.

Optionally, the composition comprises from 0.125 wt % to 0.5 wt % of thesource of stannous ions.

Optionally, the composition comprises from 0.125 wt % to 0.35 wt % ofthe source of stannous ions.

Optionally, the composition comprises from 0.15 wt % to 0.3 wt % of thesource of stannous ions.

Optionally, the source of stannous ions is stannous chloride.

Optionally, the composition comprises from 50 wt % to 65 wt % water.

Optionally, the composition comprises from 52 wt % to 60 wt % water.

Optionally, the composition comprises from 54 wt % to 55 wt % water

Optionally, the composition further comprises a fluoride ion sourceselected from the group consisting of sodium fluoride, potassiumfluoride, potassium monofluorophosphate, sodium monofluorophosphate,ammonium monofluorophosphate, sodium fluorosilicate, ammoniumfluorosilicate, an amine fluoride, ammonium fluoride, and combinationsthereof.

Optionally, the composition further comprises a source of zinc ions.

Optionally, the source of zinc ions comprises zinc oxide, zinc citrate,or mixtures thereof.

Optionally, the composition comprises zinc citrate in an amount of from0% to 1.5%, preferably, 1.5 wt % to 2.5 wt %.

Optionally, the composition comprises zinc oxide in an amount of from 0%to 1.5%, preferably 0.5 wt % to 1.5 wt %.

Optionally, the composition is a toothpaste, a tooth gel, a mouthrinse,a cream or an ointment.

Optionally, the composition is free of additional preservative agents.

The present invention also provides an oral care composition asdescribed above which has improved robustness towards microbialchallenge.

In a second aspect, the present invention provides use of a watersoluble source of stannous ions for improving the robustness towardsmicrobial challenge of an oral care composition containing at least 50wt % water, wherein the source of stannous ions is present in the oralcare composition at a concentration of from 0.1 wt % to 0.75 wt %, andwherein the source of stannous ions is selected from the groupconsisting of stannous chloride, stannous pyrophosphate, stannousformate, stannous acetate, stannous gluconate, stannous lactate,stannous tartrate, stannous oxalate, stannous malonate, stannouscitrate, stannous ethylene glyoxide, and mixtures thereof.

Optionally, the composition comprises from 0.15 wt % to 0.3 wt % of thesource of stannous ions.

Optionally, the source of stannous ions is stannous chloride.

Optionally, the composition comprises from 50 wt % to 60 wt % water.

The present inventors have surprisingly found that the addition of astannous ion source at a concentration of 0.1 wt % to 0.75 wt % to ahigh water content aqueous oral care composition (at least 50 wt % watercontent) greatly improves the robustness of the composition towardsmicrobial challenge, compared to compositions which do not contain asource of stannous ions or any other chemical reagents that areresponsible for preservation.

DESCRIPTION OF THE INVENTION

It should be understood that the detailed description and specificexamples, while indicating embodiments of the invention, are intendedfor purposes of illustration only and are not intended to limit thescope of the invention.

As used throughout, ranges are used as shorthand for describing each andevery value that is within the range. Any value within the range can beselected as the terminus of the range.

As used herein, the words “preferred” and “preferably” refer toembodiments of the invention that afford certain benefits, under certaincircumstances. However, other embodiments may also be preferred, underthe same or other circumstances. Furthermore, the recitation of one ormore preferred embodiments does not imply that other embodiments are notuseful, and is not intended to exclude other embodiments from the scopeof the invention.

As used herein, the term “about”, when applied to the value for aparameter of a composition or method of this invention, indicates thatthe calculation or the measurement of the value allows some slightimprecision without having a substantial effect on the chemical orphysical attributes of the composition or method. If, for some reason,the imprecision provided by “about” is not otherwise understood in theart with this ordinary meaning, then “about” as used herein indicates apossible variation of up to 5% in the value.

As referred to herein, all compositional percentages are by weight ofthe total composition unless otherwise indicated. As referred to herein,“ppm” (parts per million) refers to ppm by weight, unless otherwiseindicated. As referred to herein, all ratios refer to weight ratios,unless otherwise indicated.

In one aspect, the present invention provides an aqueous oral carecomposition comprising from about 0.125 wt % to about 0.75 wt % of awater soluble source of stannous ions, wherein the composition comprisesat least 50 wt % water and wherein the source of stannous ions isselected from the group consisting of stannous chloride, stannouspyrophosphate, stannous formate, stannous acetate, stannous gluconate,stannous lactate, stannous tartrate, stannous oxalate, stannousmalonate, stannous citrate, stannous ethylene glyoxide, and mixturesthereof. Alternatively, the amount of stannous ions throughout theapplication can be referred to directly, e.g. about 0.125 wt % to about0.75 wt % of stannous chloride (SnCl₂) would correlate to about 0.080 wt% to about 0.47 wt % of stannous ions.

In some embodiments, the composition comprises from about 0.15 wt % toabout 0.75 wt % of the source of stannous ions, optionally from about0.15 wt % to about 0.5 wt % of the source of stannous ions.

In some embodiments, the composition comprises from 0.15 wt % to 0.3 wt% of the source of stannous ions, optionally from 0.20 wt % to 0.25 wt %of the source of stannous ions.

In some embodiments, the composition comprises from 0.3 wt % to 0.5 wt %of the source of stannous ions, optionally 0.35 wt % to 0.45 wt % of thesource of stannous ions.

In some embodiments, the source of stannous ions is stannous chloride(SnCl₂).

The oral care compositions of the present invention are aqueous, andcomprise at least 50 wt % water. In some embodiments, the oral carecomposition comprises from 50 wt % to 65 wt % water, optionally from 52wt % to 60 wt % water, further optionally from 54 wt % to 55 wt % water.In some embodiments, the oral care composition comprises from 50 wt % to60 wt % water.

In some embodiments, the oral care compositions of the present inventionfurther comprise a fluoride ion source selected from the groupconsisting of sodium fluoride, potassium fluoride, potassiummonofluorophosphate, sodium monofluorophosphate, ammoniummonofluorophosphate, sodium fluorosilicate, ammonium fluorosilicate, anamine fluoride, ammonium fluoride, and combinations thereof. One exampleof an amine fluoride is Olaflur(N′-octadecyltrimethylendiamine-N,N,N-tris(2-ethanol)-dihydrofluoride).

In certain embodiments the fluoride ion source includes sodium fluoride,amine fluorides, sodium monofluorophosphate, as well as mixturesthereof. A preferred fluoride salt may be sodium monofluorophosphate.

In certain embodiments, the oral care composition of the invention maycontain a fluoride ion source or fluorine-providing ingredient in anamount sufficient to supply about 50 to about 5000 ppm fluoride ion,e.g., from about 100 to about 1000, from about 200 to about 500, orabout 250 ppm fluoride ion. Fluoride ion sources may be added to thecompositions of the invention at a level of about 0.001 wt % to about 10wt %, e.g., from about 0.003 wt % to about 5 wt %, 0.01 wt % to about 1wt, or about 0.05 wt %. However, it is to be understood that the weightsof fluoride salts to provide the appropriate level of fluoride ion willobviously vary based on the weight of the counter ion in the salt, andone of skill in the art may readily determine such amounts.

In some embodiments, the oral care compositions of the present inventionfurther comprise a source of zinc ions. One or more such sources can bepresent. One or more zinc ion sources may be present in a total amountof from about 0.05 wt % to about 3 wt %, for example from about 0.1 wt %to about 1 wt %, by total weight of the composition.

Suitable zinc ion sources include without limitation zinc acetate, zinccitrate, zinc gluconate, zinc glycinate, zinc oxide, zinc sulfate,sodium zinc citrate and mixtures thereof.

In certain embodiments, the source of zinc ions comprises zinc oxide(ZnO), zinc citrate, or mixtures thereof. In some embodiments, thecomposition comprises zinc citrate in an amount of from 1.5 wt % to 2.5wt %, optionally in an amount of from 1.75 wt % to 2.25 wt %.Alternatively or additionally, the composition may comprise zinc oxidein an amount of from 0.5 wt % to 1.5 wt %, optionally in an amount offrom 0.75 wt % to 1.25 wt %.

In some embodiments, the oral care compositions of the present inventionmay comprise one or more agents selected from abrasives, diluents,bicarbonate salts, pH modifying agents, surfactants, foam modulators,thickening agents, viscosity modifiers, humectants, sweeteners,flavorants, pigments, antibacterial agents, anticaries agents,anticalculus or tartar control agents, and mixtures thereof.

In some embodiments, the compositions of the present invention furthercomprise at least one abrasive.

Abrasive silicas are distinct from thickening silicas. In general,abrasive (cleaning) silicas can be characterized as having oilabsorption levels of about 40 to 150 cc/100 g and having an Einlehnerabrasion of 3 or greater mg loss/100,000 revolutions whereas thickeningabrasives have oil absorption levels of greater than 150 cc/100 g andhaving an Einlehner abrasion of less than 2 mg loss/100,000 revolutions.

Abrasives that may be used include silica abrasives such as precipitatedor hydrated silicas having a mean particle size of up to about 20microns, such as Zeodent 103, 105, 113, 114, 115, or 124 marketed byJ.M. Huber Chemicals Division, Havre de Grace, Md. 21078, Sylodent 783marketed by Davison Chemical Division of W.R. Grace & Company, SorbosilAC 43 from PQ Corporation, and mixtures thereof. Other useful dentifriceabrasives include aluminium oxide, aluminum silicate, calcined alumina,bentonite or other siliceous materials, insoluble phosphates, calciumcarbonate, and mixtures thereof.

Other possible abrasive silicas include silica gels and precipitatedamorphous silica having an oil adsorption value of less than 100 cc/100g silica and optionally in the range of from about 45 cc/100 g to lessthan about 70 cc/100 g silica. These silicas are colloidal particleshaving an average particle size ranging from about 3 microns to about 12microns, and optionally between about 5 to about 10 microns.

The abrasive or mixture of abrasives may be present in an amount of from5 to 35 wt % based on the weight of the composition, optionally from 10to 20 wt % based on the weight of the composition. The abrasive ormixture of abrasives may be present in an amount of from 12 to 17 wt %based on the weight of the composition.

In certain embodiments, the compositions may be free of abrasives.

In some embodiments, the oral care compositions of the present inventioncomprise at least one bicarbonate salt, useful for example to impart a“clean feel” to teeth and gums due to effervescence and release ofcarbon dioxide. Any orally acceptable bicarbonate can be used, includingwithout limitation, alkali metal bicarbonates such as sodium andpotassium bicarbonates, ammonium bicarbonate and the like. One or morebicarbonate salts are optionally present in a total amount of about 0.1wt % to about 50 wt %, for example about 0.5 wt % to 20 wt % or 1 wt %to 10 wt %, by total weight of the composition.

In some embodiments, the compositions of the present invention compriseat least one pH modifying agent. Such agents include acidifying agentsto lower pH, basifying agents to raise pH, and buffering agents tocontrol pH within a desired range. For example, one or more compoundsselected from acidifying, basifying and buffering agents can be includedto provide a pH of 2 to 10, or in various illustrative embodiments, 2 to8, 3 to 9, 4 to 8, 5 to 7, 6 to 10, 7 to 9, etc. Any orally acceptablepH modifying agent can be used, including without limitation,carboxylic, phosphoric and sulfonic acids, acid salts (e.g., monosodiumcitrate, disodium citrate, monosodium malate, etc.), alkali metalhydroxides such as sodium hydroxide, carbonates such as sodiumcarbonate, bicarbonates, sesquicarbonates, borates, silicates,phosphates (e.g., monosodium phosphate, trisodium phosphate,pyrophosphate salts, etc.), imidazole and the like. One or more pHmodifying agents are optionally present in a total amount effective tomaintain the composition in an orally acceptable pH range.

In a still further embodiment, the compositions of the inventioncomprise at least one surfactant. Any orally acceptable surfactant, mostof which are anionic, nonionic or amphoteric, can be used. Suitableanionic surfactants include without limitation, water-soluble salts ofC₈₋₂₀ alkyl sulfates, sulfonated monoglycerides of C₈₋₂₀ fatty acids,sarcosinates, taurates and the like. Illustrative examples of these andother classes include sodium lauryl sulfate (SLS), sodium coconutmonoglyceride sulfonate, sodium lauryl sarcosinate, sodium laurylisoethionate, sodium laureth carboxylate and sodium dodecylbenzenesulfonate. Suitable nonionic surfactants include withoutlimitation, poloxamers, polyoxyethylene sorbitan esters, fatty alcoholethoxylates, alkylphenol ethoxylates, tertiary amine oxides, tertiaryphosphine oxides, dialkyl sulfoxides and the like. Suitable amphotericsurfactants include without limitation, derivatives of C₈₋₂₀ aliphaticsecondary and tertiary amines having an anionic group such ascarboxylate, sulfate, sulfonate, phosphate or phosphonate. Betaines mayalso be used, a suitable example of which is cocoamidopropyl betaine.One or more surfactants are optionally present in a total amount ofabout 0.01 wt % to about 10 wt %, for example, from about 0.05 wt % toabout 5 wt %, or from about 0.1 wt % to about 2 wt % by total weight ofthe composition.

In some embodiments, the compositions of the invention comprise at leastone foam modulator, useful for example to increase amount, thickness orstability of foam generated by the composition upon agitation. Anyorally acceptable foam modulator can be used, including withoutlimitation, polyethylene glycols (PEGs), also known as polyoxyethylenes.High molecular weight PEGs are suitable, including those having anaverage molecular weight of 200,000 to 7,000,000, for example 500,000 to5,000,000, or 1,000,000 to 2,500,000. One or more PEGs are optionallypresent in a total amount of about 0.1 wt % to about 10 wt %, forexample from about 0.2 wt % to about 5 wt %, or from about 0.25 wt % toabout 2 wt %, by total weight of the composition.

In some embodiments, the compositions of the present invention compriseat least one thickening agent, useful for example to impart a desiredconsistency and/or mouth feel to the composition. Any orally acceptablethickening agent can be used, including without limitation, carbomers,also known as carboxyvinyl polymers, carrageenans, also known as Irishmoss and more particularly ι-carrageenan (iota-carrageenan), cellulosicpolymers such as hydroxyethylcellulose, carboxymethylcellulose (CMC) andsalts thereof, e.g., CMC sodium, natural gums such as karaya, xanthan,gum arabic and tragacanth, colloidal magnesium aluminum silicate,colloidal silica and the like. A preferred class of thickening orgelling agents includes a class of homopolymers of acrylic acidcrosslinked with an alkyl ether of pentaerythritol or an alkyl ether ofsucrose, or carbomers. Carbomers are commercially available from B. F.Goodrich as the Carbopol® series. Particularly preferred Carbopolsinclude Carbopol 934, 940, 941, 956, 974P, and mixtures thereof.

Silica thickeners such as Zeodent 115 and Zeodent 165 (both availablefrom Huber Engineered Materials) and DT 267 (available from PPGIndustries or OSC—Lianji Chemical Industry Co., Ltd.) may also be used.One or more thickening agents are optionally present in a total amountof from about 0.01 wt % to 15 wt %, for example from about 0.1 wt % toabout 10 wt %, or from about 0.2 wt % to about 5 wt %, by total weightof the composition.

In some embodiments, the compositions of the invention comprise at leastone viscosity modifier, useful for example to help inhibit settling orseparation of ingredients or to promote re-dispersibility upon agitationof a liquid composition. Any orally acceptable viscosity modifier can beused, including without limitation, mineral oil, petrolatum, clays andorganomodified clays, silica and the like. One or more viscositymodifiers are optionally present in a total amount of from about 0.01 wt% to about 10 wt %, for example, from about 0.1 wt % to about 5 wt %, bytotal weight of the composition.

In some embodiments, the compositions of the invention comprise at leastone humectant. Any orally acceptable humectant can be used, includingwithout limitation, polyhydric alcohols such as glycerine, sorbitol(particularly as a 70% solution), xylitol or low molecular weightpolyethylene glycols (PEGs) such as PEG 600. Many humectants alsofunction as sweeteners. One or more humectants are optionally present ina total amount of from about 1 wt % to about 70 wt %, for example, fromabout 1 wt % to about 50 wt %, from about 2 wt % to about 25 wt %, orfrom about 5 wt % to about 15 wt %, by total weight of the composition.

In some embodiments, a composition of the present invention comprises atleast one sweetener, useful for example to enhance taste of thecomposition. Any orally acceptable natural or artificial sweetener canbe used, including without limitation dextrose, sucrose, maltose,dextrin, dried invert sugar, mannose, xylose, ribose, fructose,levulose, galactose, corn syrup (including high fructose corn syrup andcorn syrup solids), partially hydrolyzed starch, hydrogenated starchhydrolysate, sorbitol, mannitol, xylitol, maltitol, isomalt, aspartame,neotame, saccharin and salts thereof (such as sodium saccharin),dipeptide-based intense sweeteners, cyclamates and the like. One or moresweeteners are optionally present in a total amount depending stronglyon the particular sweetener(s) selected, but typically 0.005 wt % to 5wt %, by total weight of the composition, optionally 0.005 wt % to 0.3wt %, further optionally 0.05 wt % to 0.1 wt % by total weight of thecomposition.

In some embodiments, a composition of the present invention comprises atleast one flavorant, useful for example to enhance taste of thecomposition. Any orally acceptable natural or synthetic flavorant can beused, including without limitation vanillin, sage, marjoram, parsleyoil, spearmint oil, cinnamon oil, oil of wintergreen (methylsalicylate),peppermint oil, clove oil, bay oil, anise oil, eucalyptus oil, citrusoils, fruit oils and essences including those derived from lemon,orange, lime, grapefruit, apricot, banana, grape, apple, strawberry,cherry, pineapple, etc., bean- and nut-derived flavors such as coffee,cocoa, cola, peanut, almond, etc., and other flavors, adsorbed andencapsulated flavorants and the like. Also encompassed within flavorantsherein are ingredients that provide fragrance and/or other sensoryeffect in the mouth, including cooling or warming effects. Suchingredients illustratively include menthol, menthyl acetate, menthyllactate, camphor, eucalyptus oil, eucalyptol, anethole, eugenol, cassia,oxanone, α-irisone, propenyl guaiethol, thymol, linalool, benzaldehyde,cinnamaldehyde, N-ethyl-p-menthan-3-carboxamine,N,2,3-trimethyl-2-isopropylbutanamide, 3-(1-menthoxy)-propane-1,2-diol,cinnamaldehyde glycerol acetal (CGA), menthone glycerol acetal (MGA) andthe like. One or more flavorants are optionally present in a totalamount of from about 0.01 wt % to about 5 wt %, for example, from about0.03 wt % to about 2.5 wt %, optionally about 0.05 wt % to about 1.5 wt%, further optionally about 0.1 wt % to about 0.3 wt % by total weightof the composition.

A composition of the invention may comprise at least one colorant.Colorants herein include pigments, dyes, lakes and agents imparting aparticular luster or reflectivity such as pearling agents. Any orallyacceptable colorant can be used, including without limitation talc,mica, magnesium carbonate, calcium carbonate, magnesium silicate,magnesium aluminum silicate, silica, titanium dioxide (TiO₂), zincoxide, red, yellow, brown and black iron oxides, ferric ammoniumferrocyanide, manganese violet, ultramarine, titaniated mica, bismuthoxychloride, and the like. One or more colorants are optionally presentin a total amount of from about 0.001 wt % to about 20 wt %, forexample, from about 0.01 wt % to about 10 wt %, or from about 0.1 wt %to about 5 wt %, by total weight of the composition.

The compositions of the present invention optionally comprise anantibacterial agent such as chlorhexidine, triclosan, quaternaryammonium compounds (for example benzalkonium chloride) or an additionalpreservative agent such as parabens (for example methylparaben orpropylparaben). One or more antibacterial or preservative agent isoptionally present in the composition in a total amount of from about0.01 wt % to about 0.5 wt %, optionally about 0.05 wt % to about 0.1 wt% by total weight of the composition.

In some embodiments, the composition is free of such additionalantibacterial or preservative agents.

The composition of the present invention optionally comprises a salivastimulating agent useful, for example, in amelioration of dry mouth. Anyorally acceptable saliva stimulating agent can be used, includingwithout limitation food acids such as citric, lactic, malic, succinic,ascorbic, adipic, fumaric and tartaric acids, and mixtures thereof. Oneor more saliva stimulating agents are optionally present in salivastimulating effective total amount.

The composition of the present invention optionally incorporates one ormore antisensitivity agents, e.g., potassium salts such as potassiumnitrate, potassium bicarbonate, potassium chloride, potassium citrate,and potassium oxalate; capsaicin; eugenol; strontium salts; chloridesalts and combinations thereof. Such agents may be added in effectiveamounts, e.g., from about 1 wt % to about 20 wt % by weight based on thetotal weight of the composition, depending on the agent chosen. Thecompositions of the present invention may also be used to treathypersensitivity by blocking dentin tubules when applied to a tooth.

In some embodiments, the composition of the invention further comprisesan antioxidant. Any orally acceptable antioxidant can be used, includingbutylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), vitaminA, carotenoids, vitamin E, flavonoids, polyphenols, ascorbic acid,herbal antioxidants, chlorophyll, melatonin, and mixtures thereof.

The composition of the present invention may additionally optionallycomprise a tartar control (anticalculus) agent as provided below. Tartarcontrol agents among those useful herein include salts of the specifiedagents, including alkali metal and ammonium salts. The agents include:phosphates and polyphosphates (for example pyrophosphates),polyaminopropanesulfonic acid (AMPS), polyolefin sulfonates, polyolefinphosphates, diphosphonates such as azacycloalkane-2,2-diphosphonates(e.g., azacycloheptane-2,2-diphosphonic acid), N-methylazacyclopentane-2,3-diphosphonic acid, ethane-1-hydroxy-1,1-diphosphonicacid (EHDP) and ethane-1-amino-1,1-diphosphonate, phosphonoalkanecarboxylic acids and. Useful inorganic phosphate and polyphosphate saltsinclude monobasic, dibasic and tribasic sodium phosphates, sodiumtripolyphosphate, tetrapolyphosphate, monosodium pyrophosphate, disodiumpyrophosphate, trisodium pyrophosphate, tetrasodium pyrophosphate(TSPP), tetrapotassium pyrophosphate (TKPP), sodium trimetaphosphate,sodium hexametaphosphate and mixtures thereof. Other useful tartarcontrol agents include polycarboxylate polymers and polyvinyl methylether/maleic anhydride (PVM/MA) copolymers, such as GANTREZ®.

In some embodiments, the composition of the present invention furthercomprises a nutrient. Suitable nutrients include vitamins, minerals,amino acids, and mixtures thereof. Vitamins include Vitamins C and D,thiamine, riboflavin, calcium pantothenate, niacin, folic acid,nicotinamide, pyridoxine, cyanocobalamin, para-aminobenzoic acid,bioflavonoids, and mixtures thereof. Nutritional supplements includeamino acids (such as L-tryptophan, L-lysine, methionine, threonine,levocarnitine and L-carnitine), lipotropics (such as choline, inositol,betaine, and linoleic acid), and mixtures thereof.

Embodiments of the present invention are further described in thefollowing examples. The examples are merely illustrative and do not inany way limit the scope of the invention as described and claimed.

EXAMPLES

Compositions A to G were formulated, as shown in Table 1, in order toassess the impact of different concentrations of SnCl₂ on the robustnessof a high water-content silica-based dentifrice against microbialchallenge. Each of these compositions has a high total water content(from both CP water and from the 70% sorbitol solution).

The Micro Robustness Index (MRI) of each of these compositions wasmeasured. The Micro Robustness Index is used as a quantitative measureof a composition's ability to withstand microbial challenge. The MRI isthe result from a challenge test assessing the antimicrobial efficacy ofa compound/composition against a pool of microorganisms includingBurkholderia cepacia, Enterobacter cloacae, Escherichia coli, Klesiellaoxytoca, Klebsiella pneumoniae, Serratia marcescens, Providenciarettgeri, Pseudomonas aeruginosa, Pseudomonas putida, Staphylococcusaureus, Staphylococcus saprophyticus. Samples are challenged 3 times at30 minute intervals with an innoculum of 10⁷ bacteria from the abovelisted pool. After 4, 6 and 24 hours, aliquots are tested to measure thelog reduction of bacteria. Using these data, the area under the curve(AUC) is calculated and then converted into the MRI; the higher the MRI,the greater the microrobustness of the tested composition.

The present inventors have found that an MRI of at least 0.75 isrequired in order to show that a composition has an acceptable level ofrobustness against microbial attack. MRI lower than 0.75 may notadequately reduce the pool of microorganisms and results in greater riskof microbial attack.

The Micro Robustness Index (MRI) for each of Compositions A to F areshown in Table 1 (all FIGURES are in percent by weight).

TABLE 1 A B C D E F G H Water 48.00 48.05 48.00 47.95 45.45 47.80 47.6047.35 sorbitol-70% 22.44 22.00 22.00 22.00 22.00 22.00 22.00 22.00solution Polyethylene 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 Glycol 600sodium 0.30 0.30 0.30 0.30 0.30 0.30 0.30 0.30 saccharin AC 43 5.00 5.005.00 5.00 5.00 5.00 5.00 5.00 ZnO — — — — 1.00 — — — Zinc Citrate 2.002.00 2.00 2.00 — 2.00 2.00 2.00 TSPP 0.50 0.50 0.50 0.50 1.00 0.50 0.500.50 TKPP — — — — 2.00 — — — sodium — — — — 1.00 — — — bicarbonate SnCl₂0.00 0.05 0.10 0.15 0.15 0.30 0.50 0.75 CMC 1.00 1.00 1.00 1.00 1.001.00 1.00 1.00 Xanthan 0.30 0.30 0.30 0.30 0.30 0.30 0.30 0.30 MFP 0.761.10 1.10 1.10 1.10 1.10 1.10 1.10 Silica abrasive 10.00 10.00 10.0010.00 10.00 10.00 10.00 10.00 Silica thickener 4.00 4.00 4.00 4.00 4.004.00 4.00 4.00 Sodium lauryl 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00sulfate powder Flavorant 1.20 1.20 1.20 1.20 1.20 1.20 1.20 1.20 TiO₂0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 TOTAL 100.00 100.00 100.00100.00 100.00 100.00 100.00 100.00 MRI 0.29 0.31 0.34 0.76 0.83 0.910.91 1.02 Total water 57.73 54.65 54.60 54.55 52.05 54.40 54.20 53.95content

As shown in Table 1, Compositions A-C (which contained less than 0.125wt % SnCl₂) had unacceptable MRI. This composition therefore did nothave an acceptable level of robustness towards microbial challenge.

However, it can be seen from the results in Table 1 that the high watercontent compositions which contained between 0.15 wt % and 0.75 wt %SnCl₂ gave MRI values of greater than 0.75. These compositions thereforeshow an acceptable level of robustness towards microbial challenge.While a concentration of 0.15 wt % SnCl₂ allowed the composition toattain the MRI>0.75 acceptance criteria, a concentration of 0.3 wt %SnCl₂ allowed the composition to attain an excellent result of MRI=0.91.In contrast, compositions up to 0.10 wt % SnCl₂ showed insufficient MRI,not even reaching half the 0.75 target.

While additional SnCl₂ could be added, the increase in MRI wasrelatively negligible compared to the cost of a 66% increase in SnCl₂(0.3 wt % vs. 0.5 wt %) or a 150% increase in SnCl₂ (0.3 wt. % vs. 0.75wt %). Moreover, SnCl₂, is an astringent compound that tastes even worsethan SnF₂ (which has a bitter, salty taste) and one of skill in the artwould be motivated to minimize the amount used once a requisite level ofMRI has been achieved.

Whilst particular embodiments of the invention have been illustrated anddescribed, it will be obvious to those skilled in the art that variouschanges and modifications may be made without departing from the scopeof the invention as defined in the appended claims.

1. An aqueous oral care composition comprising from 0.125 wt % to 0.75wt % of a water soluble source of stannous ions, wherein the compositioncomprises at least 50 wt % water and wherein the source of stannous ionsis selected from the group consisting of stannous chloride, stannouspyrophosphate, stannous formate, stannous acetate, stannous gluconate,stannous lactate, stannous tartrate, stannous oxalate, stannousmalonate, stannous citrate, stannous ethylene glyoxide, and mixturesthereof.
 2. The oral care composition of claim 1, wherein thecomposition comprises from 0.125 wt % to 0.5 wt % of the source ofstannous ions.
 3. The oral care composition of claim 2, wherein thecomposition comprises from 0.125 wt % to 0.3 wt % of the source ofstannous ions.
 4. The oral care composition of claim 2, wherein thecomposition comprises from 0.15 wt % to 0.3 wt % of the source ofstannous ions.
 5. The oral care composition of claim 1, wherein thesource of stannous ions is stannous chloride.
 6. The oral carecomposition of claim 1, wherein the composition comprises from 50 wt %to 65 wt % water.
 7. The oral care composition of claim 6, wherein thecomposition comprises from 52 wt % to 60 wt % water.
 8. The oral carecomposition of claim 6, wherein the composition comprises from 54 wt %to 55 wt % water.
 9. The oral care composition of claim 1, furthercomprising a fluoride ion source selected from the group consisting ofsodium fluoride, potassium fluoride, potassium monofluorophosphate,sodium monofluorophosphate, ammonium monofluorophosphate, sodiumfluorosilicate, ammonium fluorosilicate, an amine fluoride, ammoniumfluoride, and combinations thereof.
 10. The oral care composition ofclaim 1, further comprising a source of zinc ions.
 11. The oral carecomposition of claim 10, wherein the source of zinc ions comprises zincoxide, zinc citrate, or mixtures thereof.
 12. The oral care compositionof claim 11, wherein the composition comprises zinc citrate in an amountof from 1.5 wt % to 2.5 wt %.
 13. The oral care composition of claim 11,wherein the composition comprises zinc oxide in an amount of from 0.5 wt% to 1.5 wt %.
 14. The oral care composition of claim 1, wherein thecomposition is a toothpaste, a tooth gel, a mouthrinse, a cream or anointment.
 15. The oral care composition of claim 1, wherein thecomposition is free of additional antibacterial or preservative agents.16. The oral care composition of claim 1, wherein the composition hasimproved robustness towards microbial challenge.
 17. A method ofimproving the robustness of an oral care composition containing at least50 wt % water towards microbial challenge comprising adding to the oralcare composition a water soluble source of stannous ions, wherein thesource of stannous ions is present in the oral care composition at aconcentration of from 0.1 wt % to 0.75 wt %, and wherein the source ofstannous ions is selected from the group consisting of stannouschloride, stannous pyrophosphate, stannous formate, stannous acetate,stannous gluconate, stannous lactate, stannous tartrate, stannousoxalate, stannous malonate, stannous citrate, stannous ethyleneglyoxide, and mixtures thereof.
 18. The method of claim 17, wherein thecomposition comprises from 0.15 wt % to 0.3 wt % of the source ofstannous ions.
 19. The method of claim 17, wherein the source ofstannous ions is stannous chloride.
 20. The method of claim 17, whereinthe composition comprises from 50 wt % to 60 wt % water.